Higher eficiency appliance employing thermal load shifting in refrigerators having horizontal mullion

ABSTRACT

An appliance includes a cabinet; a first compartment; and a second compartment. The first compartment and the second compartment are separated by a horizontal mullion. The cabinet also typically includes a coolant system that has: a single compressor for regulating a temperature of the first compartment and a temperature of the second compartment operably connected to at least one evaporator; a shared coolant fluid connection system; and a coolant fluid spaced within the shared coolant fluid connection system used to regulate both the temperature of the first compartment and the second compartment. The compressor can provide the shared coolant at least two different pressures to at least one evaporator using the shared coolant fluid connection circuit. The ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is about 0.65:1 or greater.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/279,386, filed on Oct. 24, 2011, entitled HIGHER EFICIENCY APPLIANCEEMPLOYING THERMAL LOAD SHIFTING IN REFRIGERATORS HAVING HORIZONTALMULLION, the entire disclosure of which is hereby incorporated byreference.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present invention generally includes an appliancethat includes a cabinet with an internal volume; a first compartmenthaving an internal volume spaced within the cabinet; and a secondcompartment having an internal volume spaced within the cabinet. Thefirst compartment and the second compartment within the cabinet aretypically separated by a (horizontal) mullion to form the firstcompartment and the second compartment within the cabinet and eachcompartment has at least one access door that only accesses thatcompartment. The overall cabinet has a substantially steady state totalheat gain and the first compartment has a first compartmentsubstantially steady state heat gain. The appliance also typicallyincludes a coolant system that has: a single compressor operablyconnected to at least one evaporator where the single compressor is theonly compressor associated with the appliance for regulating atemperature of the first compartment and a temperature of the secondcompartment; a shared coolant fluid connection system that interconnectsat least the single compressor and at least one evaporator; and acoolant fluid spaced within the shared coolant fluid connection systemused to regulate both the temperature of the first compartment and thesecond compartment. The compressor can provide the shared coolant atleast two different pressures to at least one evaporator using theshared coolant fluid connection circuit. Also, the ratio of thesubstantially steady state heat gain for the first compartment to thesubstantially steady state total heat gain for the overall cabinet istypically about 0.65:1 or greater (for horizontal mullion) and the firstcompartment is at a first temperature, typically a fresh foodcompartment above freezing, and the second compartment is at a secondtemperature, typically a temperature below the temperature of the firstcompartment such as a freezer compartment. In any embodiment of thepresent invention discussed herein, the first compartment and secondcompartment may be both below freezing, both above freezing or one abovefreezing and one below freezing.

Another aspect of the present invention is directed toward an appliancethat includes a cabinet having an internal volume; a first compartmenthaving an internal volume spaced within the cabinet; and a secondcompartment having an internal volume spaced within the cabinet wherethe first compartment and the second compartment within the cabinet areseparated by a (horizontal) mullion to form the first compartment andthe second compartment within the cabinet. Each compartment typicallyhas at least one access door that only accesses that compartment and theoverall cabinet has a substantially steady state total heat gain and thefirst compartment has a first compartment substantially steady stateheat gain. The appliance also typically includes a coolant system thatincludes: a single compressor operably connected to at least oneevaporator where the single compressor is the only compressor associatedwith the appliance for regulating a temperature of the first compartmentand a temperature of the second compartment; a shared coolant fluidconnection system that interconnects at least the single compressor andat least one evaporator; and a coolant fluid spaced within the sharedcoolant fluid connection system used to regulate both the temperature ofthe first compartment and the second compartment. The coolant systemtypically has at least two modes of operation, a first mode and a secondmode, where the compressor provides the shared coolant at a firstpressure level to at least one evaporator using the shared coolant fluidconnection circuit in the first mode and the compressor provides theshared coolant at a second pressure level, which is different than thefirst pressure level, to at least one evaporator using the sharedcoolant fluid connection circuit in the second mode. The ratio of thesubstantially steady state heat gain for the first compartment to thesubstantially steady state total heat gain for the overall cabinet isabout 0.65:1 or greater (horizontal mullion). The first compartment istypically at a first temperature, typically a fresh food compartmenttemperature above freezing, and the second compartment is at a secondtemperature, typically below the temperature of the first compartmentsuch as the temperature of a freezer compartment.

Yet another aspect of the present invention includes a dual (ormultiple, two or more) evaporator and single compressor containingappliance that includes: a cabinet having an internal volume, a firstcompartment having an internal volume spaced within the cabinet, and asecond compartment having an internal volume spaced within the cabinet.The first compartment and the second compartment are separated by a(horizontal) mullion to form the first compartment and the secondcompartment within the cabinet and each compartment has at least oneaccess door that typically only accesses that compartment. The overallcabinet typically has a substantially steady state total heat gain andthe first compartment has a first compartment substantially steady stateheat gain. A first evaporator is associated with the first compartmentand operates at a first pressure level. A second evaporator isassociated with the second compartment and operates at a second pressurelevel, which is a different pressure level than the first pressurelevel. A single compressor operably connected to the first evaporatorand the second evaporator is also typically employed and the singlecompressor is typically the only compressor associated with theappliance for regulating the temperature of the first compartment andthe temperature of the second compartment. The single compressor and thefirst and second evaporators form two (or more) refrigeration circuitsthat provide a flow of coolant in a non-simultaneous manner to the firstand second evaporators such that the two refrigeration circuits providethe first evaporator and the second evaporator with adjustable loadcapacities and the ratio of the substantially steady state heat gain forthe first compartment to the substantially steady state total heat gainfor the overall cabinet is about 0.65:1 or greater (horizontal mullionconfiguration).

Another aspect of the present invention includes a method for improvingthe efficiency of an appliance. The method typically includes at leastthe steps of: 1) providing an appliance having at least twocompartments, and 2) shifting the overall thermal load of the applianceto a higher operating temperature compartment. The appliance typicallyincludes: a cabinet having an internal volume, a first compartmenthaving an internal volume spaced within the cabinet, and a secondcompartment having an internal volume spaced within the cabinet wherethe first compartment and the second compartment within the cabinet areseparated by a (horizontal) mullion to form the first compartment andthe second compartment within the cabinet. Each compartment typicallyhas at least one access door that only accesses that compartment and theoverall cabinet has a substantially steady state total heat gain and thefirst compartment has a first compartment substantially steady stateheat gain. The appliance also typically includes a coolant system thatuses: at least one evaporator; a single compressor operably connected toat least one evaporator where the single compressor is the onlycompressor associated with the appliance for regulating a temperature ofthe first compartment and a temperature of the second compartment; ashared coolant fluid connection system that interconnects at least thesingle compressor and the at least one evaporator; and a coolant fluidspaced within the shared coolant fluid connection system used toregulate both the temperature of the first compartment and the secondcompartment. The compressor typically provides the shared coolant at atleast two different pressures to at least one evaporator using theshared coolant fluid connection circuit. The step of shifting theoverall thermal load of the appliance typically includes shifting theoverall thermal load of the appliance (with a horizontal mullion) suchthat at least about 65% of the total substantially steady state heatgain of the overall cabinet is gained by the refrigeration/firstcompartment and thereby increasing the overall coefficient ofperformance of the appliance.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. For the purpose of illustrating the invention,there are shown in the drawings, certain embodiment(s) which arepresently preferred. It should be understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown. Drawings are not necessary to scale, butrelative special relationships are shown and the drawings may be toscale especially where indicated. As such, in the description or aswould be apparent to those skilled in the art. Certain features of theinvention may be exaggerated in scale or shown in schematic form in theinterest of clarity and conciseness.

FIG. 1 is a schematic of a sequential dual evaporator system that may beutilized according to an aspect of the present invention;

FIG. 2 is a thermodynamic cycle of a sequential dual evaporatorrefrigeration system that may be utilized in connection with the thermalload shifting employing methods of improving efficiency of the applianceaccording to an aspect of the present invention.

FIG. 3 is an interior schematic view of a dual evaporator refrigerationsystem according to an aspect of the present invention;

FIG. 4 shows a standard insulated bottom freezer refrigeration unit withinsulation evenly spaced around the bottom freezer compartment and inthe top refrigeration compartment;

FIG. 5 shows an aspect of the present invention incorporating greaterinsulation capacity around the bottom mount freezer;

FIG. 6 demonstrates another embodiment of shifting the overall thermalload to the fresh food compartment by thinning the insulated layeraround the fresh food compartment;

FIG. 7 shows a schematic view of a system according to the presentinvention incorporated into a top mount freezer configuration with ahorizontal oriented mullion.

FIG. 8 shows a top mount freezer with standard insulated capacity aroundthe walls of both the freezer compartment and the fresh foodcompartment;

FIG. 9 shows higher insulated capacity around the freezer compartment toshift the overall thermal load of the appliance to the fresh foodcompartment;

FIG. 10 shows lessened insulated capacity around the fresh foodcompartment than the freezer compartment in another method to shift theoverall thermal load to the refrigeration compartment.

FIG. 11 shows a schematic view of another aspect of the presentinvention showing a coolant system in a side by side appliance systemwith a vertical mullion;

FIG. 12 shows the standard insulated capacity and a side by siderefrigeration appliance;

FIG. 13 shows an increased insulated capacity around the freezercompartment to thereby shift the overall thermal load of the applianceto the fresh food compartment.

FIG. 14 shows a side by side appliance with lesser insulated capacityaround the fresh food compartment than the freezer compartment to shiftthe overall thermal load to the refrigeration compartment;

FIG. 15 shows a compressor according to an aspect of the presentinvention showing dual suction;

FIG. 16 shows another embodiment of a compressor according to an aspectof the present invention showing dual suction.

FIG. 17 shows a schematic view of another aspect of the presentinvention showing a coolant system employing three evaporators in abottom mount freezer configuration with French doors and a drawer (thirdcompartment) that may be a freezer drawer or fresh food drawercompartment.

FIG. 18 is a schematic graphical illustration of time versus temperaturewithin a freezer compartment.

DETAILED DESCRIPTION

Before the subject invention is described further, it is to beunderstood that the invention is not limited to the particularembodiments of the invention described below, as variations of theparticular embodiments may be made and still fall within the scope ofthe appended claims. It is also to be understood that the terminologyemployed is for the purpose of describing particular embodiments, and isnot intended to be limiting. Instead, the scope of the present inventionwill be established by the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range, and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges, and are also encompassed within the invention, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

In this specification and the appended claims, the singular forms “a,”“an” and “the” include plural reference unless the context clearlydictates otherwise.

The present invention is generally directed toward appliance systems andmethods for increasing the efficiency (coefficient of performance) ofthe appliance. The appliance systems may be bottom mount freezer systems(see FIG. 3), a top mount freezer system (see FIG. 7), a side by siderefrigerator and freezer system (see FIG. 11), or a french door stylebottom mount freezer system that may or may not employ a thirdcompartment, typically a drawer that may operate as a refrigeratordrawer or a freezer drawer (see FIG. 17). Generally speaking, theappliance gains efficiency by shifting the overall thermal load of theappliance 2 to a first compartment 34 from a second, lower temperature,compartment 36. The shifting of thermal load is used in conjunction withthe system that employs at least one evaporator, but can incorporatemultiple evaporators for the same or different appliance compartment.The compressor 12 may be a variable capacity compressor, such as alinear compressor. The compressor may be a single suction compressor ora dual suction compressor. When the compressor is a single suctioncompressor, it typically provides non-simultaneous dual suction from thecoolant fluid conduits 14 from the refrigeration (fresh food)compartment and the freezer compartment.

As discussed above, the coolant system 10 utilized according to anaspect of the present invention typically includes a single compressor12 operably connected to at least one evaporator 24 where the singlecompressor is typically the only compressor associated with theappliance for regulating the temperature of the first compartment 34(typically the fresh food compartment) and the temperature of a secondcompartment 36 (typically the freezer compartment). The coolant systemalso typically employs fluid conduits 14, at least one condenser 16, afilter/dryer 18, and one or more expansion devices 20, such as acapillary tube or capillary tubes. The coolant system may alsooptionally employ one or more check valves 21 that prevent back flow ofcoolant fluid in the overall coolant system. Check valves are typicallyemployed when a multiple evaporator coolant system is employed operatingin a non-simultaneous manner.

As shown in FIG. 1, one aspect of the present invention utilizes asequential dual evaporator refrigeration system as the coolant system10. The dual evaporator refrigeration system shown in FIG. 1 employs twoevaporators 24 fed by two fluid conduits engaged to two separateexpansion devices 20. Due to evaporating pressure differences needed tocool the two compartments at different operating temperatures, theevaporators cannot operate simultaneously and thus are activated ascooling is needed in a given compartment. In this sense, a majoradvantage of the dual (or multiple) evaporator system is that theevaporator in the refrigerator compartment runs at a higher temperature,thereby increasing the overall coefficient of performance. The cycleanalysis (shown in FIG. 2) indicates an approximate 28% increase in theoverall coefficient of performance in such a system. This assumes thatthe refrigeration compartment represents about ⅓ of the total heat loadand the evaporators in the refrigeration compartment and the freezercompartment operate at −15° F. (freezer compartment) and 10° F.(refrigeration compartment evaporator). The evaporators maintain therefrigeration (fresh food) compartment and the freezer compartmenttemperatures at 45° F. and 5° F. respectively.

Another aspect of the present invention includes a variation on thesystem not shown in FIG. 1. The variation includes a single evaporatorfed by two capillary tubes in alternating patterns. Such a systemrequires more fluid conduits and flow switching valves/dampers, but maybe utilized. When a single evaporator 24 is employed, the singleevaporator is typically a multi-air stream single evaporator that iscapable of receiving coolant at two different pressures from the fluidconduits that receive coolant from the compressor.

As shown in FIG. 2, the thermodynamic cycles of a sequential dualevaporator refrigeration system gains efficiency from the sequentialdual evaporator's use in connection with the refrigeration compartmentoperation. The refrigeration compartment operation enables therefrigeration system to have a much higher cycle efficiency due to thehigher operating temperature. The overall coefficient of performance isa weighted average of the coefficient of performance of the freezeroperation and the refrigeration (fresh food) compartment operation asfollows:

COP_(Total) =x×COP_(RC)+(1−x)×COP_(FC)

“x” is the ratio refrigerator compartment heat gain to the total heatgain. The same general calculation is applicable when the compartmentsare both refrigeration compartments or both freezer compartments, butwhere one compartment is operated at a higher operating temperature thananother compartment of the appliance. The overall coefficient ofperformance depends on the ratio of the refrigeration compartment heatgain to that of the entire appliance. The higher this ratio, the betterthe overall coefficient of performance. In the context of the presentinvention, the ratio of the steady state heat gain for the refrigerationcompartment (the first higher temperature compartment) to the steadystate total heat gain for the overall cabinet when the refrigerationcompartment and the freezer compartment (first compartment and secondcompartment) are separated by vertical mullion is about 0.50:1 orgreater. When the compartments are separated by a horizontal mullion,the ratio is about 0.65:1 or greater.

As discussed above, the first compartment is typically the refrigerationor fresh food compartment. The second is typically the freezercompartment. While this is the typical configuration, configurationcould conceivably be two refrigeration compartments or two freezercompartments. So long as the first compartment is at a highertemperature than the second compartment, whether both are above freezingor below freezing, efficiencies are gained. As shown in various figures,including FIGS. 3, 7 and 11, the appliance may be any of the knownconfigurations for a refrigeration appliance typically employed. Theyinclude a bottom mount freezer, a top mount freezer, and a side by sideconfiguration. In the case of the top mount and bottom mount freezer,the mullion separating the compartments is typically a horizontalmullion. In the case of a side by side configuration, the mullionseparating the two compartments is a vertical mullion. When the firstcompartment and second compartment are separated by a horizontallyoriented mullion, the ratio of the internal volume of the secondcompartment to the internal volume of the overall cabinet is about0.15:1 or greater, about 0.25:1 or greater, about 0.27:1 or greater,about 0.3:1 or greater. The ratio is typically from about 0.25:1 toabout 0.37:1. When the mullion is a vertically oriented mullion, theratio of the internal volume of the second compartment to the internalvolume of the cabinet is typically about 0.37:1 or greater.

While the ratio of the steady state heat gain for the first compartmentto the steady state total heat gain for the overall cabinet when thefirst and second compartments are separated by a vertical mullion isabout 0.50:1 or greater, this ratio may be about 0.52:1 or greater,about 0.65:1 or greater, or about 0.80:1 or greater. In the case whenthe first compartment and the second compartment are separated by ahorizontal mullion, the ratio of the substantially steady state heatgain for the first compartment to the substantially steady state totalheat gain for the overall cabinet may be about 0.65:1 or greater, about0.66:1 or greater, or, about 0.69:1 or greater. In the context of thepresent invention, the term “substantially steady state heat gain”refers to the heat gain of the appliance system (overall cabinet) orportion of the appliance system (one of the compartments) when inoperation and at its standard (user-determined) settings and at thecondition meeting those settings. The term “substantially steady stateheat gain” is meant to take into account the physical reality that theoverall appliance is never at a steady state because the interiorcompartments of the appliance are at a lower temperature than theambient air. Therefore, there is at least to some extent, decay/heatgain to the overall appliance. Applicants recognize by use of thisstatement that the overall refrigerator is in a dynamic state; however,it is meant to refer when the decay rates are slow such they seem staticover a longer period of time. For example, a decay-cooling cycle isillustrated schematically in FIG. 18. In that graph, there is a curve100 shown schematically as a linear sawtooth curve, although in realitythe segments of that curve would most likely not be linear. The curve100 represents the increase and decrease of temperature within thefreezer compartment over time. The positively sloped segments representtimes when an evaporator 24 is not being cooled and the negativelysloped portions of the curve represent those times when the evaporator24 is providing cooling. A first point in time is designated by verticalline 102 which represents the initiation of a cooling cycle, that is theinitiation of cooling by the freezer evaporator. A subsequent verticalline 104 represents a subsequent initiation of the cooling cycle by theevaporator.

An aspect of the present invention includes increasing the efficiency ofthe appliance by shifting the overall thermal load of the appliance suchthat at least 50% of the total steady state heat gain of the overallappliance is gained by the refrigeration compartment when the first andsecond compartment are separated by a vertical mullion and at leastabout 65% of the total substantially steady state heat gain of theoverall cabinet is gained by the first compartment (fresh foodcompartment) to thereby increase the overall coefficient of performanceof the coolant system of the appliance. As shown in at least FIGS. 3, 7,11 and 17, and mentioned previously, the cooling systems may beincorporated into a variety of appliance configurations, including abottom mount freezer system (FIG. 3), a top mount freezer system (FIG.7), a side by side configuration (FIG. 11), and a French doorconfiguration that may or may not further include an optional thirddrawer that may function as either a freezer or a refrigerator (freshfood) compartment (FIG. 17). Generally speaking, each of the embodimentsemploy at least two compartments, a first compartment 34, which istypically a fresh food compartment or a compartment operating at ahigher operating temperature than a second compartment 36, which istypically a freezer compartment. In the context of FIG. 17, a thirdevaporator 24 may be utilized for the third compartment 38, which, asdiscussed above, can function as a refrigerator drawer or freezerdrawer. In connection with each application, typically a singlecompressor 12 is utilized. Fluid conduits 14 provide fluid flow from thecompressor to at least one condenser 16, through a filter/dryer 18 (whenutilized), through at least one expansion device 20 such as a capillarytube or tubes, and to at least one evaporator, more typically multipleevaporators. Ultimately, fluid is returned to the compressor. Fans 32are generally positioned proximate the evaporator(s) to facilitatecooling of the compartment/heat transfer. Similarly, fans 32 may be usedin conjunction with the condenser (see FIG. 11).

The compressor 22 may be a standard reciprocating or rotary compressor,a variable capacity compressor, including but not limited to a linearcompressor, or a multiple intake compressor system (see FIGS. 15-16). Asshown in FIGS. 15-16, a compressor according to an aspect of the presentinvention may utilize a compressor system 40 that contains two coolantfluid intake streams from the refrigerator compartment or the freezercompartment evaporator(s). When a linear compressor is utilized, thelinear compressor has a variable capacity modulation, which is largerthan a 3 to 1 modulation capacity typical with a variable capacityreciprocating compressor.

FIGS. 15 and 16 generally show dual suction port compressor systems. Acondenser piston 42 and two ways of dual intake of coolant fluid areshown respectively in FIGS. 15 and 16. In the case of FIG. 15, coolantfluid is received into the piston chamber 44 from the refrigeratorcompartment and freezer compartment (first compartment and secondcompartment) fluid conduits when the piston is drawn backward, thepiston chamber valves 46 are both opened, or, when the solenoid switch48 is activated, only coolant fluid from the second compartment (freezercompartment) fluid conduit is drawn in, and the piston chamber valve 46associated with the intake from the first compartment (freshfood/refrigeration compartment) fluid conduit is not actuated, butretained in a closed position. When the piston stroke is actuated towardthe piston chamber valves, piston chamber valve 46′ is opened by fluidpressure to allow coolant fluid to pass to the condenser 16.

An alternative embodiment is shown in FIG. 16, which shows a singlepiston chamber intake valve 46, which is fed from a valving system 52.The valving system as shown by lines 54′ and 54″, which represent thehousing of the compressor, may be within the housing of the compressorwhen the housing is at position 54′ relative to the valving system andoutside of the housing when the housing is in position 54″ relative tothe valving system. The position of the housing 54 in FIG. 16 is simplymeant to display that the valving system may be outside of the housingor within the housing of the compressor. The valving system 52 employs aswitching mechanism which typically is a magnetically actuated solenoidsystem where obstruction 56 is actuated between a first position (shown)allowing refrigerant coolant to flow from the refrigeration compartmentevaporator and a second position (not shown) where the obstruction 56 ispositioned to block fluid paths from the refrigerator compartmentevaporator and allow refrigerant to flow from the freezer compartmentevaporator. In either embodiment (FIG. 15 or 16) of the dual suctionport compressor systems, the pressure of the coolant fluid leaving thecompressor for the condenser is significantly higher than the pressureof the coolant received from the refrigeration compartment or thefreezer compartment, but the pressure of the coolant received from therefrigeration compartment fluid conduit is greater than the coolantreceived from the freezer compartment fluid conduit. This, as discussedabove, allows for greater efficiencies of the overall coolant system.

As discussed generally above, the efficiency of the overall appliance isenhanced by shifting the thermal load of the coolant systems to thefirst compartment (higher temperature than the second compartment,typically the refrigeration compartment). This can be done in a varietyof manners, but typically would be accomplished by one or more of thefollowing: increasing the overall insulating capacity of the wallssurrounding the second (freezer/lower temperature) compartment;increasing the internal volume of the refrigeration compartment withoutincreasing the overall size of the appliance cabinet, and/or by reducingthe internal volume of the second (freezer/lower temperature)compartment. One or more of these ways to shift the thermal load to thefirst compartment employed in any one appliance. FIGS. 4 and 8 show abottom mount and top mount freezer configuration with no modificationswhile FIG. 12 shows a side by side system with no modifications. FIGS.5, 9 and 13 show a configuration with increased insulation capacityaround the freezer and lower freezer volume (either of these may beemployed) instead of or in addition to one another. While this is shownin the drawings as a “thicker” walled freezer, insulation systems withhigher insulative capacity may be used such that dimensions may or maynot change. FIGS. 6, 10 and 14 show a larger internal volume for thefirst compartment 34. The larger internal volume for the firstcompartment (typically the fresh food compartment) is desired by manyconsumers to hold more foodstuffs. In such a system, the overall energyusage may be the same or less than an unmodified appliance employing atraditional coolant system despite the overall increase in internalvolume of the first compartment (fresh food compartment). As discussedabove, in an alternative embodiment, vacuum insulation panels 58, orother systems of increased insulated capacity over standard insulatedwalls may be utilized around the second compartment 36 (see generallyFIG. 3). As a result, wall thickness of the appliance may or may notchange, but can depend upon the insulative systems used. The use ofhigher insulation capacity technologies such as vacuum insulation panelsin greater amount/thickness would further increase the thermal loadshift from the second compartment to the first compartment.

When the internal volume of the first compartment 34 is increased, itcan be increased to a limiting minimum wall thickness that is determinedby external condensation on the exterior for the either fresh foodcompartment or freezer compartment and freezing on the interior of thefresh food side of the mullion separating the first compartment 34,typically the fresh food compartment, and the second compartment 36,typically the freezer compartment or a compartment with a lower averagetemperature than the first compartment. Another limiting factor for wallthickness is the flow of insulation foam, typically polyurethane foam.If the space is too small, the foam will not flow properly. The firstcompartment 34 typically uses insulation foam, typically polyurethanefoam at about 37 mm. That thickness can be reduced according to thepresent invention to about 20 mm, but more typically will have a reducedthickness of less than about 30 mm, but any thickness less than thetypically used, about 37 mm could be used and some benefits seen. Thethickness of the first compartment walls can be changed by up 11.2%, upto about 14% and even as much as up to about 16% and any range betweenabout 11% and 16% from the original thickness. The overall firstcompartment volume may increase by as much as about 1.5%. The secondcompartment 36 (typically a freezer compartment) wall thickness to firstcompartment (typically a fresh food compartment) 34 wall thickness ratiois typically a ratio of about 1.35 to 1 or greater, more typically ofabout 1.4 to 1 or greater, and most typically a ratio of 1.43 to 1 orgreater. These changes may be accomplished and, according to one aspectof the present invention, no increased energy usage would be requiredover a standard configuration appliance of the same type.

Additionally, thermal storage material may also be used to furtherenhance efficiencies of the appliance. Thermal storage material 60,which can include phase changing material or metal solids, can beoperably connected to the first compartment evaporator. The thermalstorage material may be in thermal contact or engagement with the firstcompartment evaporator, in thermal contact or engagement with the fluidline operably connected to the first compartment evaporator, or inthermal contact or engagement with both. The use of the thermal storagematerial helps prevent “down” time of the compressor.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

1. An appliance comprising: a cabinet having an internal volume and comprising a first compartment having an internal volume spaced within the cabinet and a second compartment having an internal volume spaced within the cabinet where the first compartment and the second compartment within the cabinet are separated by a horizontal mullion to form the first compartment and the second compartment within the cabinet and wherein each compartment has at least one access door that only accesses that compartment and the overall cabinet has a substantially steady state total heat gain and the first compartment has a first compartment substantially steady state heat gain; a coolant system comprising: a single compressor operably connected to at least two evaporators with a first evaporator associated with the first compartment and a second evaporator associated with the second compartment and wherein the single compressor is the only compressor associated with the appliance for regulating a temperature of the first compartment and a temperature of the second compartment; a shared coolant fluid connection system that interconnects at least the single compressor and the first evaporator and the second evaporator; a coolant fluid spaced within the shared coolant fluid connection system used to regulate both the temperature of the first compartment and the second compartment; and wherein the compressor provides the shared coolant at at least two different pressures to the first evaporator and the second evaporator using the shared coolant fluid connection circuit; wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is about 0.65:1 or greater; wherein the single compressor is operably connected to the first evaporator and the second evaporator; and wherein the first compartment is at a first temperature and the second compartment is at a second temperature below the first temperature when the appliance is in operation.
 2. The appliance of claim 1, wherein the ratio of the internal volume of the second compartment to the internal volume of the cabinet is 0.27:1 or greater and wherein the first compartment is a fresh food compartment at a temperature above freezing and the second compartment is at a temperature below freezing.
 3. The appliance of claim 1, wherein the ratio of the internal volume of the second compartment to the internal volume of the cabinet is 0.3:1 or greater.
 4. The appliance of claim 1, wherein the ratio of the internal volume of the second compartment to the internal volume of the cabinet is about 0.25:1 or greater.
 5. The appliance of claim 1, wherein the ratio of the internal volume of the second compartment to the internal volume of the cabinet is about 0.15:1 or greater.
 6. The appliance of claim 5, wherein the single compressor and the first and second evaporators form two refrigeration circuits that share coolant and provide a flow of coolant fluid in a non-simultaneous manner to the first evaporator and second evaporator such that the two refrigeration circuits provide the first evaporator and the second evaporator with adjustable load capacities.
 7. The appliance of claim 6, wherein the single compressor has a single suction port and the flow of coolant is provided in a non-simultaneous manner to the first evaporator and second the second evaporator.
 8. The appliance of claim 6, wherein the single compressor has at least two suction ports and the flow of coolant is configured to provide to the first evaporator and the second evaporator in a manner chosen from the group consisting of: a simultaneous manner, a non-simultaneous manner, and both a simultaneous manner and non-simultaneous manner.
 9. The appliance of claim 6 further comprising a thermal storage material engaged with and operably connected to the first evaporator.
 10. The appliance of claim 7 further comprising a thermal storage material in thermal communication with the first compartment and the first evaporator along a coolant flow pathway.
 11. The appliance of claim 8, wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is 0.69:1 or greater.
 12. The appliance of claim 1, wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is 0.69:1 or greater.
 13. The appliance of claim 1, wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is 0.66:1 or greater.
 14. The appliance of claim 1, wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is 0.69:1 or greater, and wherein the single compressor is a variable capacity compressor.
 15. The appliance of claim 14, wherein the single compressor is a linear variable capacity compressor.
 16. An appliance comprising: a cabinet having an internal volume and comprising a first compartment having an internal volume spaced within the cabinet and a second compartment having an internal volume spaced within the cabinet where the first compartment and the second compartment within the cabinet are separated by a horizontal mullion to form the first compartment and the second compartment within the cabinet and wherein each compartment has at least one access door that only accesses that compartment and the overall cabinet has a substantially steady state total heat gain and the first compartment has a first compartment substantially steady state heat gain; a coolant system comprising: a single compressor operably connected to a first evaporator and a second evaporator wherein the single compressor is the only compressor associated with the appliance for regulating a temperature of the first compartment and a temperature of the second compartment; a shared coolant fluid connection system interconnecting at least the single compressor and the first evaporator and the second evaporator; a coolant fluid spaced within the shared coolant fluid connection system used to regulate both the temperature of the first compartment and the second compartment; and wherein the coolant system has at least two modes of operation, a first mode and a second mode, wherein the compressor provides the shared coolant at a first pressure level to at least one evaporator using the shared coolant fluid connection circuit in the first mode and the compressor provides the shared coolant at a second pressure level, which is different than the first pressure level, to at least one evaporator using the shared coolant fluid connection circuit in the second mode; wherein the ratio of the substantially steady state heat gain for the first compartment to the substantially steady state total heat gain for the overall cabinet is about 0.65:1 or greater; and wherein the first compartment is a fresh food compartment at a temperature above freezing and the second compartment is at a temperature below freezing.
 17. The appliance of claim 16, wherein the single compressor comprises a single suction port and a flow of coolant is provided in a non-simultaneous manner to the first evaporator and the second evaporator and wherein at least two access doors allow access to the first compartment wherein the single compressor is the only compressor associated with the appliance for regulating a temperature of the first compartment and a temperature of the second compartment.
 18. The appliance of claim 16, wherein the single compressor has at least two suction ports and the flow of coolant is capable of being provided in a simultaneous manner to the first and second evaporators and wherein at least two access doors allow access to the first compartment wherein the single compressor is the only compressor associated with the appliance for regulating a temperature of the first compartment and a temperature of the second compartment.
 19. A method for improving the efficiency of an appliance comprising the steps of: providing an appliance that comprises: a cabinet having an internal volume and comprising a first compartment having an internal volume spaced within the cabinet and a second compartment having an internal volume spaced within the cabinet where the first compartment and the second compartment within the cabinet are separated by a horizontal mullion to form the first compartment and the second compartment within the cabinet and wherein each compartment has at least one access door that only accesses that compartment and the overall cabinet has a substantially steady state total heat gain and the first compartment has a first compartment substantially steady state heat gain; a coolant system comprising: a single compressor operably connected to at least two evaporators with a first evaporator associated with the first compartment and a second evaporator associated with the second compartment and wherein the single compressor is the only compressor associated with the appliance for regulating a temperature of the first compartment and a temperature of the second compartment; a shared coolant fluid connection system that interconnects at least the single compressor and the first evaporator and the second evaporator; a coolant fluid spaced within the shared coolant fluid connection system used to regulate both the temperature of the first compartment and the second compartment; and wherein the compressor provides the shared coolant at a first pressure to the first evaporator and at a second pressure that is different than the first pressure to the second evaporator using the shared coolant fluid connection circuit; and shifting the overall thermal load of the appliance such that at least about 65% of the total substantially steady state heat gain of the overall cabinet is gained by the first compartment and thereby increasing the overall coefficient of performance.
 20. The method of claim 19, wherein the single compressor is operably connected to the first evaporator and the second evaporator such that the two refrigeration circuits provide the first evaporator and the second evaporator with adjustable load capacities and the single compressor is the only compressor associated with the appliance for regulating the temperature of the first compartment and the temperature of the second compartment; wherein the single compressor and the first and second evaporators form two refrigeration circuits that provide a flow of coolant to the first and second evaporators; and wherein the first compartment is a refrigeration compartment at a temperature above freezing during operation of the appliance and the second compartment in a freezer compartment at a temperature below freezing wherein the step of shifting the overall thermal load of the appliance during operation of the appliance; wherein the ratio of the internal volume of the second compartment to the internal volume of the cabinet is from about 0.25:1 to 0.37:1; and comprises at least one step chosen from the group consisting of increasing the overall insulating capacity of the walls surrounding a freezer compartment, increasing the internal volume of the refrigeration compartment without increasing the size of the cabinet, and reducing the internal volume of the freezer compartment. 